## Precalculus (6th Edition) Blitzer

$x^2=9691y$; $58\ ft$
Step 1. Using the figure given in the exercise, we can write the general form of the parabola as $x^2=4py$ Step 2. As the point $(1750,316)$ is on the parabola, we have $1750^2=4p(316)$, which gives $4p=\frac{1750^2}{316}\approx9691$. Thus the parabola is $x^2=9691y$ Step 3. To find the height at $x=1750-1000=750\ ft$, we have $y=\frac{750^2}{9691}\approx58\ ft$